Prep the apples: Peel, core, and slice the apples into thin wedges. Aim for even slices so they cook at the same rate.

Start the skillet: Heat a medium skillet over medium heat. Add 2 tablespoons butter. When melted and bubbly, stir in brown sugar, granulated sugar, cinnamon, salt, and vanilla.

Cook the apples: Add apple slices and toss to coat. Cook 6–8 minutes, stirring occasionally, until the apples soften and the sauce thickens slightly. Add lemon juice if using.

Make the crumble: While apples cook, mix oats, flour, brown sugar, salt, and optional spices in a bowl. Work in the cold butter with your fingers until it looks like coarse crumbs.

Add the topping: Sprinkle the crumble evenly over the apples in the skillet.

Crisp it up: Let it cook on the stove for 3–4 minutes, uncovered, until the topping firms up. For extra golden crunch, slide the skillet under a broiler for 1–2 minutes. Watch closely.

Serve warm: Spoon into bowls. Add vanilla ice cream, whipped cream, or a drizzle of cream if you like.